Complete interruptions of service are unacceptable in a typical voice network. For example, 911 calls and air traffic control notices may be transported over such a voice network. A complete service interruption could result in catastrophic consequences. Therefore, voice networks are designed such that voice data could be transmitted between two locations over distinct paths routes. This way, an outage of a single circuit does not result in a complete service outage for the voice network. Typically, three way diversity, or three distinct routes between data points, may be preferred for sufficient voice network robustness.
Many voice networks that exist today are combinations of multiple independent networks merged together to form a single network. Ensuring diversity in a network formed from previously independent networks has become a difficult task because the protocols and naming conventions of the several different networks are different.